Thursday, February 17, 2011

Muscles of lower limb

Psoas major: arise from the transverse processes of the lumbar vertebrae laterally

Iliacus: arise from the iliac fossa

insert in the lesser trochanter of the femur

Action:the most powerful flexor of the thigh. If the lower limb is fixed, it bends the vertebral column forward (e.g., when sitting up from supine position) and flexes the lumbar region laterally. It also can rotate the thigh laterally.

tensor fasciae latae

Actions: Flexes and abducts the hip joint. Helps to keep the knee extending in erect posture and steadies the trunk on the thigh.

Posterior group

Gluteus Maximus

Action： a powerful extensor of the thigh, the most powerful lateral rotator, and an important postural muscle.

Action: flexes the thigh and the leg, when the knee is flexed, it medially rotates the leg.

Quadriceps Femoris

Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius

Quadriceps Femoris

Origin:

Rectus femoris: anterior inferior iliac spine

Vastus medialis: medial lip of linea aspera

Vastus lateralis: lateral lip of linea aspera

Vastus intermedius: anterior surface of femur

Insertion: tibial tuberosity via patellar ligament

Action : extend the leg. rectus femoris also flexes the thigh.

Medial group

gracilis

pectineus

adductor longus

adductor brevis

adductor magnus

Actions: Adduct, flex and laterally rotate the thigh. The gracilis can adduct the hip joint and flex the knee.

posterior group

biceps femoris

semitendinosus

Semimembranosus

Actions: They are the main extensors of the thigh and flexors of the leg. When the knee joint is semi-flexed, they also can rotate the leg.

The muscles of leg

Anterior group

tibialis anterior

extensor digitorum longus

extensor hallucis longus

Actions: All the muscles of this group can dorsiflex the ankle joint. In addition, the tibialis anterior can invert the foot (the sole of the foot faces medially), the extensor hallucis longus extends the big toe, and the extensor digitorum longus extends the other toes.

Actions: Plantar flexes the ankle joint (e.g., in walking and dancing) and steadies leg on foot during standing. The gastrocnemius also can flex the knee joint.

deep layer

popliteus

flexor digitorum longus

Actions: Plantar flexes the ankle joint as well as all joints of the lateral four toes.

tibialis posterior

Actions: Flexes the ankle joint, inverts the foot.

flexor hallucis longus

Actions: plantar flexes the ankle joint and the big toe at all joints.

Muscles of the foot

extensor digitorum brevis

The muscles of the foot can be grouped into four layers, but these are difficult to dissociate, even in dissection. The muscles function either to move the toes or to support the arches of the foot through their contraction